You should install the preview only if you want to try out an operating system that is still developing. With time, you may get lots if updates and the User Interface may possibly change a lot over the time.

Backup the data:

Make sure to backup all your data because the system might crash and you may end up losing data. Some software like antivirus etc. might not work along with some hardware like printers.

The drivers for basic functions like input, output, network etc. come with the preview. These drivers might get updated later.

Things may get rough with touch:

The Windows 10 Technical Preview works well with touch, but you some things may not seem smooth enough.

Other notes:

Some older 64-bit PCs are not supported by Technical Preview.

You need a screen resolution of at least 1024×768, an internet connection and a Microsoft account to access Windows Store.